The present disclosure is generally directed to connectors for transferring signals using capacitive coupling and electron tunneling. In particular, the connectors disclosed herein are designed to transfer high frequency signals through the contact interface using capacitive coupling as opposed to traditional metallic contact (galvanic) transfer and suffer less or no signal degradation due to corrosion and/or oxidation effects. More specifically, the connectors disclosed herein can have a mating interface that have an insulating coating or film associated with the contact interface
In the past, contact resistance and voltage drop have been used to assess the performance of signal and power contacts respectively. Consequently, a great deal of research has been aimed at understanding the physics of contact interfaces in terms of metallic contact area and the impact a loss of contact area has as a system degrades in the field. However, as data rates increase, the propagation of high frequency signals requires transmission lines with sufficient bandwidth to pass the signals with minimal losses and distortion. In these cases, one must consider not only the contact resistance, but also the transmission characteristics of the connector system. This requires understanding the impedance of the connector contact including the contact interface. Consequently, one must know the level of capacitance and inductance introduced by the contact in question. With this knowledge, the impact of the contact upon signal propagation can be estimated.
Resistance and capacitance of typical multi-point contact interfaces have been used to assess the impact on high frequency signal integrity. Finite element field analysis has shown that the impedance of degraded contact interfaces can affect the transmission of high frequency signals. Research also has been done showing the relationship of wave propagation relative to contact interface physics at high frequencies in the frequency and time domains.
In addition, this research has shown that fully degraded contact interfaces can still provide acceptable performance for high frequency and high data rate signal transfers. In the case of a fully degraded contact, signals are transferred by capacitive signal coupling and wave propagation. It has also shown that the low end frequency spectrum may affect the quality of signals with significant low frequency content.
The present disclosure presents the main parameters associated with capacitive coupling of contact interfaces including the physics of the contact interface, methods for applying these parameters to determine the type and thickness of an insulating film to apply to the contact depending on the desired capacitive coupling and electron tunneling properties, and connectors with contacts having an insulating film or coating associated thereto for capacitive as opposed to galvanic coupling for signal transfer. It will be understood that application of the present disclosure to particular fields of use also can require consideration of other factors such as the overall geometric effects of the entire contact structure from one end of the connector path to the other along with transmission line characteristics which can impact signal integrity.